Abstract:

For conventional reservoir, NMR is an effective technology that can be used to evaluate petrophysics and pore structure, distribution and saturation of pore fluid rapidly, nondestructively and economically. Applying NMR technologies to evaluate shale reservoir, however, often encounters problems such as low resolution and inapplicable interpretation and evaluation models, due to reservoir characteristics such as nanoscale pore, complex mineral composition, complex pore structure, high organic content, ultralow permeability, influence of internal field gradients and restricted diffusion et al. In this paper, we reviewed recent progresses in NMR technologies for shale oil and gas exploration and exploitation, and related data analysis methods. Special attention was given to areas such as improvement of NMR detection resolution and novel evaluation models for pore structure, rock physical property, and pore fluid distribution and recognition. Two areas needed further research are identified: relaxation mechanisms inside nano-pore and improving pore scale resolution of D-T₂. Petrophysics evaluation model and pore fluid evaluation model also need to be further optimized.

Key words: shale, resolution, NMR, pore structure, pore fluid